Referral Store Finder App

I am launching a mobile app that lets shoppers see participating store locations on a live map, check-in when they walk through the door, and instantly invite friends from their phone contacts to join them. When an invited friend shows up, the store grants that friend an on-the-spot discount while boosting the reward balance of the person who sent the invite—turning every visit into an easy referral loop.

The build needs to run natively on both iOS and Android from a single codebase. Phone-number verification will be the only sign-in method, so please factor in an SMS OTP flow. For mapping and in-store positioning I want Google Maps SDK with smooth zoom, pin clustering, and real-time distance calculations. Stores will appear, the user taps “I’m here,” and the app records the visit, unlocks the referral screen, and fires a push notification to selected contacts with the invite link.

Core deliverables
• Cross-platform mobile app (iOS & Android) compiling without errors
• Phone number authentication flow (SMS OTP)
• Google Maps integration with store pins, search, and “check-in” logic
• Contact picker that lets users choose friends, send the referral, and track status
• Simple reward ledger showing earned discounts and referral points

I am open to Flutter or React Native backed by Firebase (Firestore, Auth, Cloud Functions) or an equivalent stack you propose—so long as it stays lightweight, secure, and easy to scale as more stores sign on.

Once the MVP is running smoothly, I’ll look to add geofencing, NFC check-in, and a merchant portal, so clean, modular code is important. If this brief matches your skill set, I’d love to see a concise plan of attack and a rough timeline for completion of the above milestones.